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[snp] Allocate additional padding for receive buffers

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Some SNP implementations (observed with a wifi adapter in a Dell
Latitude 3440 laptop) seem to require additional space in the
allocated receive buffers, otherwise full-length packets will be
silently dropped.

The EDK2 MnpDxe driver happens to allocate an additional 8 bytes of
padding (4 for a VLAN tag, 4 for the Ethernet frame checksum).  Match
this behaviour since drivers are very likely to have been tested
against MnpDxe.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown
2024-03-16 23:25:07 +00:00
parent 17882e76af
commit bac967d51a
1 changed files with 14 additions and 1 deletions
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15
src/drivers/net/efi/snpnet.c
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@@ -71,6 +71,19 @@ struct snp_nic {
/** Delay between each initialisation retry */
#define SNP_INITIALIZE_RETRY_DELAY_MS 10
/** Additional padding for receive buffers
*
* Some SNP implementations seem to require additional space in the
* allocated receive buffers, otherwise full-length packets will be
* silently dropped.
*
* The EDK2 MnpDxe driver happens to allocate an additional 8 bytes of
* padding (4 for a VLAN tag, 4 for the Ethernet frame checksum).
* Match this behaviour since drivers are very likely to have been
* tested against MnpDxe.
*/
#define SNP_RX_PAD 8
/**
* Format SNP MAC address (for debugging)
*
@@ -246,7 +259,7 @@ static void snpnet_poll_rx ( struct net_device *netdev ) {
/* Allocate buffer, if required */
if ( ! snp->rxbuf ) {
snp->rxbuf = alloc_iob ( snp->mtu );
snp->rxbuf = alloc_iob ( snp->mtu + SNP_RX_PAD );
if ( ! snp->rxbuf ) {
/* Leave for next poll */
break;